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A101753
Numbers m such that Sum_{k=0..m} m^k is prime.
1
1, 2, 6, 126, 8598
OFFSET
1,2
COMMENTS
Value of sum for m = 126 has been checked to be probably prime with the isprime functions of PARI and Maple V. Also checked with ECM - see link.
Note that m+1 must be prime and hence a(n) = A088856(n) - 1. Another way to compute the number is (m^(m + 1) - 1)/(m - 1). - T. D. Noe, Dec 15 2004
Value of sum for m = 126 has been certified prime with Primo. - Ryan Propper, Jul 11 2005
FORMULA
a(n) = A088856(n) - 1.
EXAMPLE
The number 6 is in this sequence because 6^0 + 6^1 + 6^2 + 6^3 + 6^4 + 6^5 + 6^6 = (6^7 - 1)/5 = 55987 is prime.
CROSSREFS
Cf. A031973.
Cf. A088856 (primes p such that cyclotomic(p,p-1) is prime).
Sequence in context: A164955 A060001 A181316 * A288185 A359961 A274695
KEYWORD
nonn,more
AUTHOR
Mark Hudson (mrmarkhudson(AT)hotmail.com), Dec 15 2004
EXTENSIONS
One more term from T. D. Noe, Dec 15 2004
Edited by Thomas Ordowski, Sep 02 2021
STATUS
approved